Hi all! I have a question about the RS flats.... I just got a pair of regular denim ones (not caged) in size 40 and there's a bit of a gap in the back, 39.5 was too snug, but my question is: are they comfortable considering how low they are cut around the foot or would the caged ones be more comfortable around the foot? I'm guessing with the caged ones you they wouldn't slip off the foot that easy? I love them but I'm a little concerned about this and have not worn them yet for this reason in case I end up returning them for the caged ones. Any insight you can provide would be great! Thanks so much!